From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AE266412C14; Mon, 10 Aug 2026 15:26:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786375562; cv=none; b=GNNC0I1PhFYlJNMZOv4FgqTrS4Akudcu6EU3iJMdSL7Q4dx4LRv98lGWyGlrFHrZxrwikQRo+jMmn/z6u0oqcAIcyjrE7payVitDAQCMt6zpVv9bpth8nXAwRue8kEVJ0zajp9rCcECsZU5mQDAh2O/u5Y2su03kiwVaddqPOPg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786375562; c=relaxed/simple; bh=cBbEuBXDYGfvTczhgMtrEgmzqHHgNaR3v5+5iJE1Tvs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=g2z3Wg7/JIJLdJGgJnU7LwwUgvlFfayoiPjlU6DeiV5KrqLP/BWcU6jlH7+GmqqGMU+pAa/wrdSi0wpDtXuyklFQbbODBIOxUAZJTfidotMWJ2jZE7vDIvMLsqOHGSLqaI5qi8xWLi3J0C1M36mmj2bDKitC3EseQJp8SNqNLwg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lEVVy+Rl; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lEVVy+Rl" Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id E48D71F000E9; Mon, 10 Aug 2026 15:26:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786375561; bh=R6XGNIoHTxlsz/t6Ux5E4FYc5dcadC245O5UcI4QIWU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=lEVVy+RlGR7iKBSWGUV0tR0j3SPbLz2UPic+KDLB9+hCAMXYa4bF596SqhJz/iijw Q1n1ucMYrlWNV22lXhAyiuOxe6pXyVTO48Whqq82x0+hnRJ2NKRdSdJsFiKYNfwf6w MBx+a3KlQutMvZd7rDbjqKHmyfucbBNfrGdqwH5uXY322BxTpjYcpwhzh6ip20RiDm RgSCnU8Zij5jIWb3igScPdhoBgW+AMWVOF064FFU5+ua3NVq/RmR3xUar5cAdB6DIF IxgJwnDZwyV812DRjRxmzq+ZBRAllmrjwI7k7d94iSDyJAtROADXPPYwtBqz5MUk59 CW+G3FveO6n4Q== Date: Mon, 10 Aug 2026 18:25:53 +0300 From: Jarkko Sakkinen To: Chengfeng Ye Cc: James Bottomley , Mimi Zohar , David Howells , Paul Moore , James Morris , "Serge E. Hallyn" , Roberto Sassu , linux-integrity@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] KEYS: trusted: Fix TPM teardown ordering Message-ID: References: <20260731140925.2973492-1-nicoyip.dev@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260731140925.2973492-1-nicoyip.dev@gmail.com> On Fri, Jul 31, 2026 at 10:09:24PM +0800, Chengfeng Ye wrote: > trusted_tpm_exit() drops the TPM chip reference and frees the digest > array before unregistering the trusted key type. key_type_lookup() > holds key_types_sem for reading until the key operation finishes, while > unregister_key_type() takes it for writing. It therefore provides the > synchronization point that must precede backend teardown. > > The current order permits this interleaving: > > CPU 0 CPU 1 > trusted_tpm_exit() key_type_lookup("trusted") > put_device(&chip->dev) trusted_tpm_seal() > kfree(digests) pcrlock() > unregister_key_type() tpm_pcr_extend(..., digests) > > CPU 1 can consequently dereference the freed digest array. The chip can > also be released before callbacks stop using it. > > KASAN reported: > > BUG: KASAN: slab-use-after-free in tpm_pcr_extend+0x1f0/0x200 > Read of size 2 at addr ffff88810872d000 by task poc/89 > Call Trace: > tpm_pcr_extend+0x1f0/0x200 > pcrlock+0x42/0x70 [trusted] > trusted_tpm_seal+0x1b6/0x570 [trusted] > trusted_instantiate+0x293/0x340 [trusted] > __key_instantiate_and_link+0xb2/0x2b0 > __key_create_or_update+0x61e/0xb50 > __do_sys_add_key+0x1b8/0x310 > Allocated by task 88: > __kmalloc_noprof+0x1a7/0x490 > do_one_initcall+0xa1/0x390 > do_init_module+0x2df/0x840 > Freed by task 90: > kfree+0x131/0x3c0 > trusted_tpm_exit+0x59/0xa0 [trusted] > __do_sys_delete_module+0x346/0x510 > > Move unregister_key_type() before releasing either resource. This stops > new lookups and waits for in-flight key operations to finish before the > backend state is destroyed. Thank for the great report. > > Fixes: 0b6cf6b97b7e ("tpm: pass an array of tpm_extend_digest structures to tpm_pcr_extend()") > Cc: stable@vger.kernel.org > Signed-off-by: Chengfeng Ye > --- > security/keys/trusted-keys/trusted_tpm1.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c > index 13513819991e..8f57c6111e7e 100644 > --- a/security/keys/trusted-keys/trusted_tpm1.c > +++ b/security/keys/trusted-keys/trusted_tpm1.c > @@ -987,9 +987,9 @@ static int __init trusted_tpm_init(void) > static void trusted_tpm_exit(void) > { > if (chip) { > + unregister_key_type(&key_type_trusted); > put_device(&chip->dev); > kfree(digests); > - unregister_key_type(&key_type_trusted); > } > } > > -- > 2.43.0 > Reviewed-by: Jarkko Sakkinen BR, Jarkko